Redispersible Polymer Powder Supplier

Frequently Asked Questions

• Q: What is the difference between VAE and acrylic RDP grades?
• A: VAE (vinyl acetate-ethylene) RDP is the most widely used grade in construction, offering a good balance of flexibility, adhesion, and cost. Acrylic RDP (styrene-acrylic or pure acrylic) provides superior UV resistance and hydrophobicity, making it preferred for exterior-facing applications such as EIFS finish coats, colored renders, and other products exposed to prolonged sunlight and weather. VAE grades are recommended for interior and below-grade applications; acrylic grades for exposed exterior finishes.

• Q: What dosage of RDP is typically used in tile adhesive?
• A: For C1 (standard) tile adhesive, RDP is not required. For C2 (improved adhesion, ≥1.0 N/mm²), typical RDP dosage is 1–2% by weight of dry mix. For C2S1 (deformable) or C2S2 (highly deformable) adhesives, dosage increases to 2–4% and 3–5% respectively. Exact dosage depends on the specific RDP grade selected, the cement content of the formulation, and the required adhesion and deformability classifications.

• Q: Can RDP be used in gypsum-based formulations?
• A: Yes. RDP is compatible with gypsum-based products and is used in gypsum-based EIFS systems, gypsum tile adhesives, and finishing plasters to improve flexibility and adhesion. However, gypsum environments accelerate the hydrolysis of vinyl acetate groups over time in highly alkaline conditions — this is less of a concern in gypsum systems (pH ~7–8) than in high-pH cementitious systems. For long-term exterior gypsum applications, acrylic RDP grades are preferred for their better hydrolysis resistance.

• Q: How does RDP affect the compressive strength of mortar?
• A: At typical construction dosages (1–5%), RDP moderately reduces the compressive strength of mortar compared to the pure cementitious baseline because the flexible polymer film interrupts the rigid cement matrix. However, this reduction is acceptable in most applications and is more than offset by the improvements in flexibility, adhesion, and durability. For repair mortars requiring high compressive strength, lower RDP dosages (1–2%) are recommended, and formulation should be verified against the relevant EN or ASTM standard before application.

• Q: What is the minimum film formation temperature (MFFT) and why does it matter?
• A: MFFT is the lowest temperature at which the polymer particles in the redispersed emulsion will coalesce into a continuous film. Below the MFFT, the particles remain discrete and do not form a film, significantly reducing the polymer's contribution to flexibility and adhesion. Yisheng's VAE RDP grades have an MFFT of 0–5°C, meaning they are effective in fresh mortars applied and cured at temperatures above 5°C — which covers most practical construction conditions. For cold-climate applications, confirm your application temperature is above the MFFT of the selected grade.

• Q: Does Yisheng supply RDP test data for formulation development?
• A: Yes. Technical data sheets include all key physical parameters. For customers developing new formulations, our applications team can provide trial samples with recommended starting dosages, competitive benchmarking data, and test reports covering adhesion pull-off strength, deformability, water absorption, and open time — all tested in representative mortar matrices using standard EN test methods. Contact our technical sales team to request a formulation development support package.